1. Field of the Invention
The present invention relates to thin film magnetic heads. In particular the invention relates to an improved pole tip design for thin film magnetic heads.
2. Description of the Prior Art
Thin film magnetic read/write heads are used for magnetically reading and writing information on a magnetic storage medium such as a magnetic disk or a magnetic tape. It is highly desirable to provide high levels of information storage densities on the magnetic storage medium.
One design criteria in a recording system is to provide an areal density as high as possible for a given recording surface without compromising the performance/cost ratio. In the case of rotating disk drives (both floppy and hard discs) the areal density is found by multiplying the number of flux reversals per unit length along the track (linear density in units of flux reversals per inch) by the number of tracks available per unit length along the radial direction (track density in units of tracks per inch). The areal density has shown a steady increase, doubling about every other three years. A state-of-the-art density is about 100 million bits per inch squared, and the commercial magneto-optic disc has an areal density of 480 million bits per inch squared.
In the past, great efforts have been devoted to maximizing the linear density. A higher linear density can be attained by reducing the gap length of the recording head. Furthermore, most attention has been paid to improving the media's characteristics to support shorter magnetic domain transitions such that a higher bit density is realized. This has been successfully accomplished mainly through a better understanding of the recording physics and micromagnetics. For instance, magnetic media made by deposition processes which lead to a morphology of isolated particles will have a better resolution and higher signal-to-noise ratios. T. Chen, and T. Yamashita, IEEE Trans Mag. MAG-24 (1988) p. 2700.
To further boost the areal density, a great opportunity lies in the avenue of increasing track density. It would be particularly useful if this could be done using the positive photoresist presently widely in use through out the industry.